Red Lion Graphite and Analog Scale Help

[aspainter]

I have an automated batching system that im using an analog scale to trigger automated valves to open and close. I have the programming done and works fine. My problem is getting the tag to display the right scale weight. I have a 0/10V voltage coming out of my scale and going to the analog input module in the Graphite HMI. It is reading and displaying a number just not the right one! How do I make the numbers match up? Something with the PV? Thanks in advance for any help!!

 

[OkiePC]

I've never used the built in modules, but I suspect you will need to scale a raw number to your engineering units.

I assume you have a tag that has the analog input as its source. On that tag, look at the Data Scaling properties and set them up according to your needs.

 

[aspainter]

You are correct, I have a numeric tag with an analog input source. I'm not familiar with scaling. The weight scale uses 0/10 Volts and I need to convert that back to pounds in the HMI. How would I go about that using Scaling? Thank you.

 

[OkiePC]

Is it safe to assume the data source returns a floating point number of 0.0 to 10.0 vdc?

In any case, on the Data Scaling for "Data From:" put whatever number represents zero volts, and in "Data To:" put the value that represents ten volts.

In "Display From:" put whatever number of pounds is the same as zero volts (perhaps zero?) and in "Display To:" put the number of pounds that is indicated by ten volts.

You may also need to choose Scale to Floating point in the drop down list above these four values. I would also go ahead and populate the format tab of the tag with a meaningful Label, and choose a Format Type of Numeric, then put a Units label of " pounds" or " lbs".

I like to put a single space at the beginning of my units for most tags so that they're more readable than running right up against the numeric value.

Now with all that done, you can drag and drop your tag on a screen and it should look nice "out of the box". Note that dragging and dropping tags is done by picking them from the resource pane on the right.

Also be aware that the scaling values do not have to be constants. They could be other tags or internal tags that you can edit at run time. If you use internal tags for scaling, be sure and make them retentive so they will be maintained after you adjust them.

 

[aspainter]

On the Data to and From values will that be a general number like 0 for 0 volts and 10 for 10volts or will that need to be a mapped value from the input? Like processmin or max? And on the I/O Modules there is a PV @ 0% and PV at 100% the accepted values are -300.0 to +300.0. Do these need to be adjusted? They are on 0% and 100% default. Thank you.

 

[OkiePC]

On the Data to and From values will that be a general number like 0 for 0 volts and 10 for 10volts or will that need to be a mapped value from the input? Like processmin or max? And on the I/O Modules there is a PV @ 0% and PV at 100% the accepted values are -300.0 to +300.0. Do these need to be adjusted? They are on 0% and 100% default. Thank you.

I have no idea what numbers you will get from the module. EDIT: I happen to be working on a Graphite application so I added a module to see what I could see. I am pretty sure (but can't prove) that you will get an integer back from the module channel PV and it will depend on how you set the numbers up in the module settings. If you want volts times 100, you could set it for 0.00 to 10.00 percent. When I selected three decimal points, the value for PV at 100% dropped to +30.000 and when I assign a tag, there is no option for floating point. These are my best guesses, no guarantee.

Or do this:
Make a new tag and don't scale it at all.

Test it and see what you get at zero and ten volts and go with those values in your "pounds" tag.

 

[aspainter]

Thank you! I will use this information and see if I can apply it to make this thing work! I appreciate your time!